Just found that there are several different kinds of source for LiveView intermedia product which
is fed to HDMI .
1) 12bits_1664x1088 source
2) 12bits_4928x2400 source
3) 12bits_4928x1400 source
Firmware activates 2) or 3) if dist_x10_ent.field_39E4.bit6:5 == 1 ,
dist_x10_ent.field_39E4 comes from struc_79.field_39F0 .
I even found 14bits 1664x1088 source setting for liveview at 0x241A00 .
The key point now is how to activate 2) or 3) , and change setting of chip4001 to get
12bits LV stream , firmware uses setting 1) now for normal Liveview , see code at 0x00121774 in the following screenshot .
EDIT : setting 2) , 3) are strongly related to sensor , EI155 task code , however still a mess to me .